FAQ:Why allow zero stretching at all?

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Zero Stretching or Analog Mode is not part of the NMRA DCC Standard. Manufacturers added that feature to make DCC more attractive in the early years, as many modellers were concerned about the cost of conversion.

This allowed DC locomotives to be controlled without adding a multifunction decoder. Today it is not as important as it was 30 years ago when DCC was introduced.

Analog compatibility mode is only one use for zero stretching.

Other possible uses include the following:

  1. Providing a stretched zero after each packet for the purpose of superimposing locomotive feedback to the command station.
  2. Allowing generation of the command control signal with a computer using a standard serial port, which may not be possible without slightly stretching some zeros.
  3. There are probably other uses that will become apparent as time goes on. Note that the above-mentioned uses are still very much in the experimental stages. The point is that preserving the ability to stretch zeros allows for the possibility of some interesting things.